1. Field of the Invention
The present invention relates to a contour sander. More particularly, the invention relates to a flexible sander and/or spreader for use on single or compound curved surfaces and also can be used to flatten surfaces.
2. Description of Related Art
One of the more common uses of contour sanders is repairing automobile body panels. Automobile body panels are typically made of light-weight metals, fiberglass, or plastic materials that are relatively thin. The panels are shaped into contoured (curved) body lines to provide strength and aerodynamic features for the body panels. The contoured body lines may include convex or concave curves, scooped areas, and/or channels. The sanders used on the body panels may have an adjustable curvature to allow the sander to conform to different shaped body panels and allow the sander to be used on multiple body panels and/or automobiles. The curvature of the sander may be adjusted to conform to the curvature of a specific body panel to provide accurate sanding on the body panel surface (e.g., sanding of the body panel to return the body panel as close to its original shape as possible).
U.S. Pat. No. 6,554,113 to Wheeler, which is incorporated by reference as if fully set forth herein, discloses a flexible sanding apparatus with adjustable curvature. This flexible sanding apparatus uses a flexible foam rubber handle with a thick profile. The flexibility of the foam rubber handle is controlled by the insertion/removal of three rods inside the handle. Flexing the foam rubber handle may, however, create build up in the handle because the top stretches as the handle is bent and the bottom portion does not compress since it is attached to a flat spring. The flat spring in the foam rubber handle is only bent by pressing down on the ends of the foam rubber handle. However, it may take significant pressure to bend the ends of the foam rubber handle down to curve the handle and the handle may have a limited amount of bend that prevents the handle from having the ability to work on smaller radius curves.
Because high pressure is needed to bend the flexible sanding apparatus described in U.S. Pat. No. 6,554,113 to Wheeler, the curve of the flexible sanding apparatus is determined by the profile of the surface being sanded instead of the curve being determined by the desire of the user (e.g., how much the user wants the sander to curve). In addition, when high pressure is applied, the flexible sanding apparatus may not provide the desired arc because of the thickness and stiffness of the flexible sanding apparatus. In some situations, the flexible sanding apparatus may require substantially equal high pressure to be applied substantially simultaneously to both the ends of the foam rubber handle to make it meet the contours of the surface. Providing high pressure substantially simultaneously to the ends may, however, be tiring to a user and not allow the user to have any “feel” for the contour of the body panel being worked on by the user.
Another problem with the flexible sanding apparatus described in U.S. Pat. No. 6,554,113 to Wheeler is that the foam rubber handle may bend backward (e.g., bend with the ends going away from the surface) when pressure is applied to the foam rubber handle. Thus, when sanding a relatively flat surface, the low spots on the flexible sanding apparatus may be lower than desired, making it difficult to obtain a flat sanding surface.
Thus, there is a need for a sander/spreader that has variable flexibility that is determined by the user without needing high pressure to curve the sander/spreader. The sander/spreader may be easily flexed by the user to conform to various curved surfaces with different curvatures while also allowing the sander/spreader to maintain a relatively flat profile when needed (e.g., when used on a flat surface). The sander/spreader may also allow for sanding of convex and/or concave profiles without bunching or crumpling of the sanding surface (e.g., sandpaper attached to the sander/spreader).